Ryan Hall, a two-time Olympian who has run the fastest marathon ever by an American, will race on March 15 in the LA Marathon , which serves as the 2015 USA Marathon Championships, he announced via Twitter on Christmas Eve. “Going back to where it all began, southern CA, excited to finally run it,” wrote Hall, who grew up at altitude in Big Bear, California. Hall clocked a 2:04:58 for third place at the 2011 Boston Marathon , which is not a “record-eligible” course. He ran a 2:06:17 in London in 2008, putting him second on the all-time U.S. marathon list behind Khalid Khannouchi, whose best was 2:05:38. But Hall’s most recent marathon, a 20th place 2:17:50 in Boston this past April, was the first 26.2-miler he’d completed since he was second at the 2012 U.S. Olympic Marathon Trials in 2:09:30. He had dropped out of the London Olympic marathon with a hamstring injury, and s...